GIS Dictionary
Definitions for GIS terms related to operations such as analysis, GIS modeling and web-based GIS, cartography, and Esri software.
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DEM
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[data models]
Acronym for digital elevation model. The representation of continuous elevation values over a topographic surface by a regular array of z-values, referenced to a common datum. DEMs are typically used to represent terrain relief. 
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[data models]
A format for elevation data, tiled by map sheet, produced by the National Mapping Division of the USGS.
